Spacer layer for dye diffusion transfer film

ABSTRACT

Novel photographic products for use in color diffusion transfer systems employing a neutralizing layer for lowering the environmental pH after application of an aqueous alkaline processing fluid and a &#39;&#39;&#39;&#39;timing&#39;&#39;&#39;&#39; or spacer layer so disposed with respect to the neutralizing layer that the processing fluid must first diffuse through the spacer layer before contacting the neutralizing layer, the essence of the invention being employing as the spacer layer comprising, as a continuous phase, the coalesced essence of an aqueous filmforming synthetic polymer dispersion which is substantially impermeable to the processing fluid and a discontinuous phase consisting essentially of polyvinyl alcohol.

v United States Patent George et al.

[54] SPACER LAYER FOR DYE DIFFUSION TRANSFER FILM [75] Inventors: LouisJ. George, Somerville; Ronald A. Sahatjian, Bedford, both of Mass.

[73] Assignee: Polaroid Corporation, Cambridge,

Mass.

[22] Filed: Dec. 26, 1972 [21] Appl. No.: 318,402

[52] US. Cl 96/3, 96/29 D, 96/77 [51] Int. Cl. G03c 7/00, G03c 5/54,G03c 1/40 [58] Field of Search 96/3, 29 D, 77, 76 R [56] ReferencesCited UNITED STATES PATENTS 3,362,821 l/1968 Land 96/3 3,421,892 l/1969Taylor 96/3 3,575,700 4/1971 Taylor 96/3 3,615,422 7 10/1971 Haberlin96/29 D 3,625,685 12/1971 Autges et al 96/3 3,748,129 7/1973 Autges etal 96/3 3,785,815 l/l974 Autges et al 96/3 [4 Dec. 24, 1974 PrimaryExaminer-Norman G. Torchin Assistant ExaminerRichard L. SchillingAttorney, Agent, or FirmAlvin lsaacs; John P. Morley 57 ABSTRACT Novelphotographic products for use in color diffusion transfer systemsemploying a neutralizing layer for lowering the environmental pH afterapplication of an aqueous alkaline processing fluid and a timing orspacer layer so disposed with respect to the neutralizing layer that theprocessing fluid must first diffuse through the spacer layer beforecontacting the neutralizing layer, the essence of the invention beingemploying as the spacer layer comprising, as a continuous phase, thecoalesced essence of an aqueous filmforming synthetic polymer dispersionwhich is substantially impermeable to the processing fluid and adiscontinuous phase consisting essentially of polyvinyl alcohol.

18 Claims, No Drawings SPACER LAYER FOR DYE DIFFUSION TRANSFER FILMBACKGROUND OF THE INVENTION Various diffusion transfer systems forforming color images have heretofore been disclosed in the art.Generally speaking, transfer image formation is obtained by exposing aphotosensitive element or negative component comprising at least onelight-sensitive silver halide layer having associated therewith a dyeimageproviding material (which may be a complete dye or a dyeintermediate, e.g., acolor coupler) to form a developable image;thereafter developing this image by applying an aqueous alkalineprocessing fluid; forming, as a function of this development, animagewise distribution of soluble and diffusible dye image-providingmaterial; and transferring this imagewise distribution, at least inpart, by diffusion, to a superposed imagereceiving element or positivecomponent including a dyeable stratum to impart thereto a color transferimage, usually a positive image.

The dye image-providing materials which may be employed in suchprocesses generally may be characterized as being (1) either initiallysoluble or diffusible in the processing composition but which areselectively rendered non-diffusible in an imagewise pattern as afunction of development; or (2) initially insoluble or non-diffusible inthe processing composition but which are selectively rendered diffusiblein an imagewise pattern as a function of development. Numerous examplesof both types of image-providing materials are recited in the patentliterature. A particularly useful class of such materials are dyedevelopers (dyes which are also silver halide developing agents)described in U.S. Pat. No. 2,983,606 and many other patents.

In any of these systems, multicolor images may be obtained by employinga photosensitive element or negative component including at least twoselectively sensitized silver halide layers, each having associatedtherewith a dye image-providing material exhibiting desired spectralabsorption characteristics. The most commonly employed elements of thistype are the so-called tripack structures employing a blue-, a greenanda red-sensitive silver halide layer having associated therewith,respectively, a yellow, a magenta and a cyan dye image-providingmaterial.

The negative and positive components may be ini-' tially separateelements which are brought into superposition during development andthereafter retained together or separated to provide the desiredtransfer image (e.g., as described in the aforementioned U.S. Pat. No.2,983,606); or they may be contained together as a unitary structure,e.g., the so-called integral negative-positive film units wherein therespective components are retained together prior to exposure andfollowing image-formation. In the latter systems wherein the two areretained together, a reflecting layer, usually a white pigment such astitanium dioxide, is provided between the respective components, eitheras a preformed layer or during development, so as to mask effectivelythe negative component and to provide the desired background for viewingthe image formed in the positive component as a reflection print. Therespective components in such integral film units may be contained on asingle dimensionally stable layer or support or they may be confinedbetween a pair of such supports. Of course, any support associated withthe positive component should be transparent to permit viewing of thetransfer image.

As examples of such integral negative-positive film units for preparingcolor transfer images viewable without separation, mention may be madeof those described in U.S. Pat. Nos. 3,415,644; 3,415,645;

3,689,262; 3,690,879; and others.

In the photographic systems described above employing an aqueousalkaline processing composition, it is well known to employ anacid-containing layer (neutralizing layer) to lower the environmental pHfollowing substantial dye transfer. Employment ofa neutralizing layer,and specific materials useful therein are described in U.S. Pat. Nos.3,362,8l9 and 3,362,821 as well as in many of the aformentioned patents.In those systems employing a neutralizing layer, it is common to disposean inert interlayer or spacer layer (sometimes referred to in the patentliterature as a timing layer) between the applied processing fluid andthe neutralizing layer in order to control the pH reduction, e.g., totime" control the diffusion to the neutralizing layer and subsequent pHreduction. Suitable timer layers are described in the aforementionedU.S. Pat. No. 3,362,819 and many others.

The copending application of Avtges et al., Ser. No. 246,779 filed Apr.24, 1972, now U.S. Pat. No. 3,785,815 describes and claims timing layerscomprising, as a continuous phase, the coalesced essence of an aqueousfilm-forming synthetic polymer dispersion which is substantiallyimpermeable to the aqueous alkaline processing fluid, e.g., a latex, anda discontinuous phase comprising a material sometimes referred to as apermeator which is permeable to the processing fluid.

Preferred latices disclosed in that application include a 60-38-2copolymer of methylmethacrylate, butylacrylate and acrylic acid,respectively; a 60-30-4-6 copolymer of butylacrylate, diacetoneacrylamide, styrene and methacrylic acid, respectively; and a60-30-4-6-l.5-0.5 copolymer of butylacrylate, diacetone acrylamide,styrene, methacrylic acid, 2- sulfoethyl methacrylate and diviniylbenzene, respectively, all proportion designations being on a dry weightbasis. Among other useful latices, mentionmay be made of polyvinylchloride, vinyl chloride-vinyl acetate copolymers, acrylic polymers andcopolymers as, for example, a terpolymer of butylacrylate,methylmethacrylate and small amounts of acrylic acid or methacrylicacid, and innumerable other latices which will readily come to mind toone of ordinary skill in polymer chemistry. An extensive compilation ofappropriate latices which may be utilized herein will be found in U.S.Pat. No. 2,795,564.

Useful permeators disclosed in that application include isopropylcellulose, preferably containing about 1.3 isopropyl groups percellulosic monomer unit, hydroxypropyl cellulose, acrylonitrile acrylicacid copolymers, methacrylate acrylic acid copolymers, preferablycontaining about 3% by weight acrylic acid, poly-N- ethyl acrylamide,polyacrylamide, polyethylene oxide, terpolymers of N-ethylacrylamide,methylacrylamide and acrylamide, copolymers of N-ethylacrylamide and2-vinyl pyridine, copolymers of N-isopropyl acrylamide and N-vinylpyrrolidone, copolymers of N-isopropyl acrylamide and dimethylaminoethylacrylate, etc. Other useful permeators include graft copolymers of thetype disclosed in the aforementioned U.S. Pat. No. 3,575,701 and whichare disclosed in this patent as providing useful timing layers.

As is described in that application, the coalesced latex portion of thetiming layer is denoted as the continuous phase," while the permeatorcomponent is denoted as the discontinuous phase. Such'terminologyconnotes an admixture of the two components with the former componentbeing present in greater concentration than the latter which may, ifdesired, be present in the form of continuous channels, etc., throughoutthe coalesced latex. The ratio of latex .to permeator employed may varyin accordance with the particular rate or degree of diffusibilitydesired in the photographic system in which it is employed. It will beappreciated that as the concentration of permeator increases, thepermeability of the layer also increases. A typical latex/permeatortiming layer of this invention may contain a ratio of latex to permeatoron the order of from about 19:1 to about 99:1, a typical ratio being onthe order of about 40:1. However, the selection of the particular ratiosof ingredients to be employed in a given film unit will be readilyapparent to those skilled in the art and the ratios given above areaccordingly by way of illustration only.

Generally speaking, the timing layers of this invention possess a totalthickness such that, if the layer consisted only of the coalesced latex,it would be impermeable to the alkaline processing fluid. It may, forexample, be on the order of 0.1 to 0.7 mil thick and may, for example,contain on the order of 300-1700 mgs. of solids/sq. ft. of surface area.Where employed in systems wherein the photosensitive strata are to beexposed and/or the resulting image is to be viewed through this layer,it is desirable that the layer, like any other layers through whichexposure is to be made and/or the image viewed, should be as thin aspossible. In such instances, it will also be appreciated that the timinglayer of this invention should also be as clear or transparent tovisible light as possible. To achieve such clarity, it is important thatthe latex and permeator be compatible, since incompatibility will resultin a film which may not be as transparent or clear as desired and is notmacroscopically homogenous. With various latex/permeator mixtures, itwill be appreciated that various degrees of compatibility may beachieved. The indicativeness of such compatibility may be appreciated bythe clarity of the ultimate film produced light scatter being aconcomitant result of the absence of compatibility between the latex andthe permeator used therewith, and being further indicative of the degreeof macromolecular nonhomogeneity. It will therefore be recognized thatthe discontinuities provided within the coalesced latex film by thepermeator must, in such instances, be sufficiently small so as toobviate the induction of scattering of light incident thereon. The layermay be considered to be homogeneous if the coalesced latex contains apermeator which is distributed compatibly throughout the coalesced latexfilm so as not to produce scattering of incident light. In absoluteterms, that is, on the microscopic level, the layer will generallyconsist essentially of the coalesced latex with a multiplicity of smalllocalized areas comprising the permeator.

SUMMARY OF THE INVENTION The present invention is directed to timinglayers of the type described in the aforementioned copending applicationSer. No. 246,779 and photographic systems of the type previouslydescribed employing such timing layers, the essence of the inventionbeing employing polyvinyl alcohol as the permeator to achieve certainadvantages to be described hereinafter.

DETAILED DESCRIPTION OF THE INVENTION In the photographic systemswherein the positive component is a separate element (as distinguishedfrom integral negative-positive film units) including a neutralizinglayer, this component or image-receiving element generally comprises asuitable support which may be opaque or transparent, e.g., a paper basesupport having the desired neutralizing layer, e.g., an acid layer ofthe type described in U.S. Pat. No. 3,362,819, a timing layer comprisinga latex of the type described in the aforementioned copendingapplication Ser. No. 246,779 with polyvinyl alcohol as the permeator;and a dyeable stratum such as any of those heretofore known, e.g., ofthe type described in U.S. Pat. No. 3,148,061 comprising polyvinylalcohol and poly-4- vinyl pyridine. Other reagents such as stabilizers,development restrainers, UV light absorbers and the like may be andfrequently are also present and the presence or absence of suchadditional reagents performing specific desired functions per secomprises no part of this invention.

A typical image-receiving element of the foregoing description may, forexample, comprise a paper base support having thereon, in order, a layerabout 0.8 mil thick comprising the partial butyl ester ofpolyethylene/maleic anhydride copolymer prepared in accordance withExample 10 of U.S. Pat. No. 3,362,819; a timing layer about 0.3 milthick containing about a :1 ratio of a 60-30-4-6 copolymer ofbutylacrylate,

diacetone acrylamide, styrene and methacrylic acid and polyvinylalcohol, e.g., Elvanol 72-60" (trade name of E. I. duPont de Nemours &Co. for high viscosity, hydrolyzedpolyvinyl alcohol); and a dyeablestratum or receiving layer about 0.4 mil thick comprising a 2:1 mixture,by weight, of polyvinyl alcohol and poly-4-vinylpyridine.

In lieu of having the neutralizing and timing layers associated with thepositive component, as in the foregoing example, they may be disposed inthe negative component, as disclosed in U.S. Pat. No. 3,362,821, or inboth.

The preferred integral negative-positive film units contemplated by thisinvention are of the type disclosed in U.S. Pat. No. 3,415,644 whereinthe essential layers of the negative and positive components areconfined between a pair of support members, the one associated with thenegative component being opaque and the one associated with the positivecomponent being transparent for exposure of the film unit and subsequentviewing of the resulting color image by reflected light. In essence,such a configuration for forming multi-color images may comprise, inorder, a transparent support, a neutralizing layer, a timing layer ofthis invention, a dyeable stratum, a blue-sensitive silver halideemulsion layer having a yellow dye image-providing material associatedtherewith in the same or in an adjacent layer, a green-sensitive silverhalide emulsion layer having a magenta dye image-providing materialassoci ated therewith in the same or in an adjacent layer, ared-sensitive silver halide emulsion layer having a cyan dyeimage-providing material associated therewith in the same or in anadjacent layer, and an opaque support. Preferably, an interlayer orspacer layer is disposed between each set of silver halide andassociated dye image-providing material, e.g., an interlayer of the typedescribed in U.S. Pat. No. 3,625,685 comprising a latex and a permeator.In accordance with the present invention, the permeator so employed inthese negative interlayers may be polyvinyl alcohol as in the timinglayers of this invention. The negative and positive components arepreferably prelaminated in accordance with the precedures described andclaimed in US. Pat. Nos. 3,652,281 or 3,652,282 in such a manner thatdelamination occurs at this interface upon application of an aqueousalkaline processing fluid to permit development and transfer imageformation, relamination being accomplished by the presence of a viscousreagent in the processing fluid to maintain the integrity ofthe finalprint. In addition to the essential photographic reagents, theprocessing composition also contains a reflecting agent, e.g., adispersion of titanium dioxide, so that the thus applied layer maskseffectively the negative component (including developed silver and anyassociated dye image-providing material) and provides the requisitebackground for viewing the color transfer image by reflected light,without separation, through the transparent support. Preferably, theprocessing composition also contains additional opacifying agent whichin combination with the opaque support provides a lighttight envelopesandwiching the negative component so that the film unit may bedeveloped in the light. This lastmentioned concept is described in manyof the aforementioned patents, a preferred system being that describedin US. Pat. No. 3,647,437 wherein the processing composition includesone or more optical filter agents (sometimes called indicator dyes)which are highly colored at the alkaline pH of the processing fluid butwhich are cleared" or rendered substantially transparent at a lower pHfollowing neutralization so as not to interfere with viewing of thetransfer image.

An illustrative integral negative-positive fllm unit of this descriptionmay be prepared, for example, by coating, in succession, on a gelatinsubbed 4 mil. opaque polyethylene terephthalate film base, the followinglayers:

l. a layer of cyan dye developer dispersed in gelatin and coated at acoverage of about 75 mgs./ft. of dye and about 80 mgs./ft. of gelatin;

2. a red-sensitive gelatino silver iodobromide emulsion coated at acoverage of about 140 mgs./ft. of silver and about 70 mgs./ft. ofgelatin;

3. a layer of a 60-30-4-6 copolymer of butylacrylate, diacetoneacrylamide, styrene and methacrylic acid and polyacrylamide coated at acoverage of about 150 mgs./ft. of the copolymer and about 5 mgs/ft. ofpolyacrylamide;

4. a layer of magenta dye developer dispersed in gelatin and coated at acoverage ofabout mgs./ft. of dye and about 67 mgs./ft. of gelatin;

5. a green-sensitive gelatino silver iodobromide emul sion coated at acoverage of about mgs./ft. of silver and about 40 mgs./ft. of gelatin;

6. a layer containing the copolymer referred to above in layer 3 andpolyacrylamide coated at a coverage of about mgs./ft, of copolymer andabout 12 mgs./ft.' of polyacrylamide;

7. a layer of yellow dye developer dispersed in gelatin and coated at acoverage of about 83 mgs./ft. of dye and about 64 mgs./ft. of gelatin;

8. a blue-sensitive gelatino silver iodobromide emulsion layer includingthe auxiliary developer 4'- methylphenyl hydroquinone coated at acoverage of about mgs./ft. ofsilver, about 60 mgs./ft. of gelatin andabout 30 mgs./ft. of auxiliary developer; and

9. a layer of gelatin coated at a coverage of about 50 mgs./ft. ofgelatin.

The three dye developers employed above may be the following:

a magenta dye developer; and

a yellow dye developer.

Then a transparent 4 mil. polyethylene terephthalate film base may becoated, in succession, with the following illustrative layers:

l. the partial butyl ester of polyethylene/maleic anhydride copolymerprepared by refluxing, for 14 hours, 300 grams of high viscositypoly-(ethylene/maleic anhydride), 140 grams of n-butyl alcohol and 1 cc.of 85 percent phosphoric acid to provide a polymeric acid layer at acoverage of about 2500 mgs./ft.

2. a timing layer containing about a 40:1 ratio of a 60-30-4 -6copolymer of butylacrylate, diacetone acrylamide, styrene andmethacrylic acid and polyvinyl alcohol at a coverage of about 500mgs./ft. and

3. a 2:1 mixture, by weight, of polyvinyl alcohol andpoly-4-vinylpyridine, at a coverage of about 400 mgs./ft. to provide apolymeric image-receiving layer.

The two components may then be laminated together to provide the desiredintegral film unit.

A rupturable container comprising an outer layer of lead foil and aninner liner or layer of polyvinyl chloride retaining an aqueous alkalineprocessing solution may than be fixedly mounted on the leading edge ofeach of the laminates, by pressure-sensitive tapes,,interconnecting therespective container and laminates so that, upon application ofcompressive pressure to the container to rupture the containers marginalseal, its contents may be distributed between the dyeable stratum (layer3 of the positive component) and the gelatin layer (layer 9) of thenegative component.

An illustrative processing composition to be employed in the rupturablecontainer may comprise the following properties of ingredients:

Water 100 cc.

Potassium hydroxide 112 gms. Hydroxyethyl cellulose (high viscosity)[commercially available from Hercules Powder Co., Wilmington,

Delaware. under the trade name Natrasol 250] 3.4 gms.Nphenethyl-a-picolinium bromide 2.7 gms. Benzotriazole l.lgms. Titaniumdioxide 50.0 gms. (A) 2.08 gms.

the Hisi i-on, @501-h-N-C uHzs-n This film unit may then be exposed inknown manner to form a developable image and the thus exposed elementmay then be developed by applying compressive pressure to the rupturablecontainer in order to distribute the aqueous alkaline processingcomposition, thereby forming a multicolor transfer image which isviewable through the transparent polyethylene terephthalate film base asa positive reflection print.

The use of polyvinyl alcohol as the permeator in lieu of permeators suchas polyacrylamide disclosed in the aforementioned copending applicationSer. No. 246,779, provides certain significant advantages, chief ofwhich are from the standpoint of preparation of the layers, especiallycommercial production.

The layers of this invention may be prepared simply and efficiently byadmixing the polyvinyl alcohol, latex and any other solids together inthe desired amounts in a single pot process. As distinguished from thissimple procedure, permeators such as polyacrylamide can not be soadmixed and the polyacrylamide must first be put into solution. Thistakes up to 24 hours and requires storage in drums for subsequent use incommercial production.

in addition to the slow solution and storage problems with suchpermeators, variances in the amount of permeator solids in these drumsof permeator solution makes it difficult to obtain permeator-latexlayers having the precise ratio of permeatorto latex so that thephotographic usage of the film units is constant and reproducible. Thislatter problem is of course not insurmountable but requires qualitycontrol analyses and tests which are not the mostdesirable procedurefrom the standpoint oflarge-scale commercial production. All of theseproblems are solved simply and efficiently by employment of polyvinylalcohol.

In addition, quite surprisingly the use of polyvinyl alcohol has givenevidence of improved photographic results. Specifically, it givesevidence of better performance during development at cold temperatureswhile maintaining the same performance at room temperatures and higher.Thus, polyvinyl alcohol gives evidence of better performance over thetemperature scale from hot to cold in terms of time controlling thediffusion of alkali and subsequent pH reduction within the prescribedtime sequence in the development process.

As will be appreciated by those skilled in the art, the permeator andlatex forming the layer should be com patible in the sense that they donot interact to absorb and/or reflect light. it has been found thatpolyvinyl alcohol will so interact when alkali is added to adjust thepH, e.g., at pH 7, to produce a haze. In systems such as theillustrative integral negative-positive film unit wherein viewing iseffected through this layer, this of course is undesirable and thisneutralization step heretofore suggested should be obviated. Forexample, without neutralization, e.g., at pH 4.5, the layer is perfectlyclear and performs its desired function in the prescribed manner.

The haze resulting from neutralization of course is not a problem insystems wherein the timing and neutralizing layers are so disposed inthe product, e.g., in the negative component, that they are not in thepath of viewing light. Moreover, it doesvnot appear to be a problem inthose systems wherein the layers are so disposed in the image-receivingelement which is sepa rated after image formation. While the exactreason is not entirely clear, the haze problem appears to be a surfacephenomenon which is obviated in these systems.

in any event, for purposes of clarity, the spacer layer of thisinvention may, if desired, include alkali to adjust the pH, it beingunderstood that if this pH adjustment causes undesirable haze, it shouldnot be done. In either case, the spacer layers of this invention willprovide the advantages noted above.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintendedthat all matter contained in the above description shall beinterpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a photographic product comprising a photosensitive elementincluding at least one light-sensitive silver halide layer having a dyeimage-providing material associated therewith and an image receivingelement including a dyeable stratum adapted for receiving a dye imagepattern and a neutralizing system integrated with said photosensitivesystem or said image receiving element for lowering the pH of an aqueousalkaline processing composition; said neutralizing system including aneutralizing layer and a spacer layer arranged on a support and whereinsaid spacer layer is disposed with respect to said neutralizing layer sothat said processing fluid must first diffuse through the spacer layerbefore contacting the neutralizing layer;

the improvement wherein said spacer layer com-' prises as a continuousphase a coalesced aqueous film-forming synthetic polymer dispersionwhich is substantially impervious to said processing fluid and adiscontinuous phase comprising polyvinyl alcohol.

'2. A product as defined in claim 1 wherein said neutralizing layer andsaid spacer layer are disposed between said support and saidphotosensitive system.

3. A product as defined in claim 1 wherein said support is transparentand said spacer is disposed between said dyeable stratum and saidneutralizing layer and said photosensitive system is diposed on the sideof said dyeable stratum opposed from said spacer and neutralizinglayers.

4. A product as defined in claim 1 wherein said spacer layer is disposedbetween said dyeable stratum and said neutralizing layer.

5. In an integral negative-positive film unit including a negativecomponent comprising at least one lightsensitive silver halide layerhaving a dye imageproviding material associated therewith, a positive.component including at least a dyeable stratum, means for applying areflecting layer between said positive and negative components in anamount sufficient upon development of said film unit to mask effectivelysaid negative component and toprovide a background for viewing a colorimage imparted to said dyeable stratum of said positive component byreflected light by applying an aqueous alkaline processing fluid to saidfilm unit after exposure thereof, said film unit further including aneutralizing layer for lowering the environmental pH subsequent toapplication of said alkaline processing fluid and a spacer layer sodisposed with respect to said neutralizing layer that said processingfluid must first diffuse through said spacer layer before contactingsaid neutralizing layer;

the improvement wherein said spacer layer comprises as a continuousphasea coalesced aqueous film-forming synthetic polymer dispersion whichis substantially impermeable to said processing fluid and adiscontinuous phase comprising polyvinyl alcohol.

6. A film unit as defined in claim 5 wherein said dye image-providingmaterials are initially soluble or diffusible in said aqueous alkalineprocessing fluid but are selectively rendered non-diffusible in animagewise pattern as a function of development.

7. A film unit as defined in claim 5 including means for applying saidaqueous alkaline processing fluid to develop said film unit.

8. A film unit as defined in claim 5 wherein said negative and positivecomponents are confined between a pair of support members at least thesupport member associated with said positive component beingtransparent.

9. A film unit asdefined in claim .5 wherein said positive and negativecomponents are carried on a trans parent support member associated withsaid positive component.

10. A film unit as defined in claim 5 wherein said means for applying areflecting layer comprises a layer of a white pigment disposed in alayer between said positive and negative components.

11. A film unit as defined in claim 5 including at least two selectivelysensitized silver halide layers, each hav' in g asso ciated therewith adye image-providing material, a nd a layer intermedia t e saidsilverhalide layers comprising as a continuous phase: the coalesced essence ofan aqueous film-forming synthetic polymer dispersion which issubstantially impermeable to said processing fluid and a discontinuousphase comprising polyvinyl alcohol.

12. A film unit as defined in claim 11 wherein said layer intermediatesaid silver halide layers and said spacer layer are substantially thesame.

sensitive and a red-sensitive silver halide layer having associatedtherewith, respectively, a yellow, magenta and a cyan dyeimage-providing material, a neutralizing 1 layer for lowering theenvironmental pH after application of an aqueous alkaline processingfluid to develop said film unit, and a spacer layer so disposed in saidfilm unit with respect to said neutralizing layer that said alkalineprocessing fluid must diffuse through said spacer layer beforecontacting said neutralizing layer;

the improvement wherein said spacer layer comprises as a continuousphase a coalesced aqueous film-forming synthetic polymer dispersionwhich is substantially impermeable to said processing fluid and adiscontinuous phase comprising polyvinyl alcohol. 14. In aphotosensitive element which comprises, in

combination:

a. a support layer;

b. at least two selectively sensitized silver halide layers each havingassociated therewith a dye imageforming material of predetermined color;and

c. a layer intermediate said silver halide layers comprising, as acontinuous phase, a coalesced aqueous film-forming synthetic polymerdispersion adapted to provide a dye image-forming material imperme layerand associated dye image-providing material being'separated from thenext adjacent silver halide layer and associated dye image-providingmaterial by one of said intermediate layers.

16. In a photographic process wherein a photographic product comprisinga photosensitive element including at least one light-sensitive silverhalide layer having a dye image-providing material associated therewithis exposed to form a developable image and thereafter an aqueousalkaline processing fluid is applied between the thus exposedphotosensitive element and a superposed image-receiving element todevelop said image and to impart to said receiving element a colordiffusion transfer image and said photographic product includes aneutralizing system integrated with said photosensitive elementor saidimage receiving element; said neutralizing system including aneutralizing layer and a spacer layer arranged on a support and whereinsaid spacer layer is disposed with respect to said neutralizing layer sothat said processing fluid must first diffuse through the spacer layerbefore contacting the neutralizing layer;

the improvement wherein said spacer layer comprises as a continuousphase a coalesced aqueous film-forming synthetic polymer dispersionwhich is substantially impervious to said processing fluid and adiscontinuous phase comprising polyvinyl alcohol.

17. A process as defined in claim 16 wherein said photosensitive andimage-receiving elements are separate during photoexposure.

18. In a photographic process wherein a film unit is exposed andthereafter developed by applying to the thus exposed element an aqueousalkaline processing fluid to provide a composite print viewable, withoutseparation, as a reflection print;

the improvement comprising employing as said film unit a film unit asdefined in claim 5.

1. IN A PHOTOGRAPHIC PRODUCT COMPRISING A PHOTOSENSITIVE ELEMENT INCLUDING AT LEAST ONE LIGHT-SENSITIVE SILVER HALIDE LAYER HAVING A DYE IMAGE-PROVIDING MATERIAL ASSOCIATED THEREWITH AND AN IMAGE RECEIVING ELEMENT INCLUDING A DYEABLE STRATUM ADAPTED FOR RECEIVING A DYE IMAGE PATTERN AND A NEUTRALIZING SYSTEM INTEGRATED WITH SAID PHOTOSENSITIVE SYSTEM OR SAID IMAGE RECEIVING ELEMENT FOR LOWERING THE PH OF AN AQUEOUS ALKALINE PROCESSING COMPOSITION, SAID NEUTRALIZING SYSTEM INCLUDING A NEUTRALIZING LAYER AND A SPACER LAYER ARRANGED ON A SUPPORT AND WHEREIN SAID SPACER LAYER IS DISPOSED WITH RESPECT TO SAID NEUTRALIZING LAYER SO THAT SAID PROCESSING FLUID MUST FIRST DIFFUSE THROUGH THE SPACER LAYER BEFORE CONTACTING THE NEUTRALIZING LAYER, T THE IMPROVEMENT WHEREIN SAID SPACER LAYEER COMPRISES AS A CONTINUOUS PHASE A COALESCED AQUEOUS FILM-FORMING SYNTHETIC POLYMER DISPERSION WHICH IS SUBSTANTIALLY IMPROVERVIOUS TO SAID PROESSING FLUID AND A DISCONTINUOUS PHASE COMPRISING POLYVINYL ALCOHOL.
 2. A product as defined in claim 1 wherein said neutralizing layer and said spacer layer are disposed between said support and said photosensitive system.
 3. A product as defined in claim 1 wherein said support is transparent and said spacer is disposed between said dyeable stratum and said neutralizing layer and said photosensitive system is diposed on the side of said dyEable stratum opposed from said spacer and neutralizing layers.
 4. A product as defined in claim 1 wherein said spacer layer is disposed between said dyeable stratum and said neutralizing layer.
 5. In an integral negative-positive film unit including a negative component comprising at least one light-sensitive silver halide layer having a dye image-providing material associated therewith, a positive component including at least a dyeable stratum, means for applying a reflecting layer between said positive and negative components in an amount sufficient upon development of said film unit to mask effectively said negative component and to provide a background for viewing a color image imparted to said dyeable stratum of said positive component by reflected light by applying an aqueous alkaline processing fluid to said film unit after exposure thereof, said film unit further including a neutralizing layer for lowering the environmental pH subsequent to application of said alkaline processing fluid and a spacer layer so disposed with respect to said neutralizing layer that said processing fluid must first diffuse through said spacer layer before contacting said neutralizing layer; the improvement wherein said spacer layer comprises as a continuous phase a coalesced aqueous film-forming synthetic polymer dispersion which is substantially impermeable to said processing fluid and a discontinuous phase comprising polyvinyl alcohol.
 6. A film unit as defined in claim 5 wherein said dye image-providing materials are initially soluble or diffusible in said aqueous alkaline processing fluid but are selectively rendered non-diffusible in an imagewise pattern as a function of development.
 7. A film unit as defined in claim 5 including means for applying said aqueous alkaline processing fluid to develop said film unit.
 8. A film unit as defined in claim 5 wherein said negative and positive components are confined between a pair of support members at least the support member associated with said positive component being transparent.
 9. A film unit as defined in claim 5 wherein said positive and negative components are carried on a transparent support member associated with said positive component.
 10. A film unit as defined in claim 5 wherein said means for applying a reflecting layer comprises a layer of a white pigment disposed in a layer between said positive and negative components.
 11. A film unit as defined in claim 5 including at least two selectively sensitized silver halide layers, each having associated therewith a dye image-providing material, and a layer intermediate said silver halide layers comprising as a continuous phase the coalesced essence of an aqueous film-forming synthetic polymer dispersion which is substantially impermeable to said processing fluid and a discontinuous phase comprising polyvinyl alcohol.
 12. A film unit as defined in claim 11 wherein said layer intermediate said silver halide layers and said spacer layer are substantially the same.
 13. In a film unit including a blue-sensitive, a green-sensitive and a red-sensitive silver halide layer having associated therewith, respectively, a yellow, magenta and a cyan dye image-providing material, a neutralizing layer for lowering the environmental pH after application of an aqueous alkaline processing fluid to develop said film unit, and a spacer layer so disposed in said film unit with respect to said neutralizing layer that said alkaline processing fluid must diffuse through said spacer layer before contacting said neutralizing layer; the improvement wherein said spacer layer comprises as a continuous phase a coalesced aqueous film-forming synthetic polymer dispersion which is substantially impermeable to said processing fluid and a discontinuous phase comprising polyvinyl alcohol.
 14. In a photosensitive element which comprises, in combination: a. a support layer; b. at least two selectively sensitized silver halide layers each having associated tHerewith a dye image-forming material of predetermined color; and c. a layer intermediate said silver halide layers comprising, as a continuous phase, a coalesced aqueous film-forming synthetic polymer dispersion adapted to provide a dye image-forming material impermeable polymeric layer upon coalescence and, as a discontinuous phase, a processing composition permeable material adapted to render said intermediate layer permeable to processing composition solubilized dye image-forming material subsequent to contact of said layer with said processing composition; the improvement wherein said permeable material of said discontinuous phase comprises polyvinyl alcohol.
 15. A film unit as defined in claim 14 including a blue-sensitive, a green-sensitive and a red-sensitive silver halide layer having associated therewith, respectively, a yellow, a magenta and a cyan dye image-providing material, at least one of said silver halide layer and associated dye image-providing material being separated from the next adjacent silver halide layer and associated dye image-providing material by one of said intermediate layers.
 16. In a photographic process wherein a photographic product comprising a photosensitive element including at least one light-sensitive silver halide layer having a dye image-providing material associated therewith is exposed to form a developable image and thereafter an aqueous alkaline processing fluid is applied between the thus exposed photosensitive element and a superposed image-receiving element to develop said image and to impart to said receiving element a color diffusion transfer image and said photographic product includes a neutralizing system integrated with said photosensitive element or said image receiving element; said neutralizing system including a neutralizing layer and a spacer layer arranged on a support and wherein said spacer layer is disposed with respect to said neutralizing layer so that said processing fluid must first diffuse through the spacer layer before contacting the neutralizing layer; the improvement wherein said spacer layer comprises as a continuous phase a coalesced aqueous film-forming synthetic polymer dispersion which is substantially impervious to said processing fluid and a discontinuous phase comprising polyvinyl alcohol.
 17. A process as defined in claim 16 wherein said photosensitive and image-receiving elements are separate during photoexposure.
 18. In a photographic process wherein a film unit is exposed and thereafter developed by applying to the thus exposed element an aqueous alkaline processing fluid to provide a composite print viewable, without separation, as a reflection print; the improvement comprising employing as said film unit a film unit as defined in claim
 5. 